1. Field of the Invention
The present invention relates to an image process for a video image. More particularly, the present invention relates to a technique for producing a video image obtained by increasing at least one of a resolution and a frame rate of a captured video image by an image process.
2. Description of the Related Art
U.S. Pat. No. 3,971,065 discloses a technique for recording a color image using a single imager. For example, FIG. 15 shows an example of a color filter array having an arrangement called a “Bayer arrangement” to be attached to a single imager of U.S. Pat. No. 3,971,065. In the figure, “R”, “G” and “B” denote “red”, “green” and “blue” filters, respectively (the same designation will be used hereinafter and in the drawings).
Light which has passed through the color filter of the Bayer arrangement shown in FIG. 15 is incident upon pixels of the imager. A signal output from each pixel of the imager has a value of a color of one of R, G and B.
As is clear from the description, each “pixel” of the imager is a unit portion of the imager that receives light having passed through a color filter of a color so as to output a signal according to the intensity of the received light.
On the other hand, when displaying an image captured as described above, there are needed values of R, G and B (or three colors of Y, Pb and Pr, etc.) for each pixel. In view of this, each of three following documents: Daniel Keren, Margarita Osadchy, “Restoring subsampled color images”, Machine Vision and Applications, 11, pp. 197-202, 1999; Ron Kimmel, “Demosaicing: Image Reconstruction from Color CCD Samples”, IEEE Transactions on Image Processing, Vol. 8, No. 9, September 1999; and David Alleysson, Sabine Su{umlaut over ( )}sstrunk, “Linear Demosaicing Inspired by the Human Visual System”, IEEE Transactions on Image Processing, Vol. 14, No. 4, April 2005, discloses a method for obtaining a color image with a large number of pixels by restoring, through arithmetic operations, pixel values of colors that have not been obtained for each pixel of the imager, thereby obtaining R, G and B pixel values for each pixel of the imager.
However, with conventional imaging and processing devices, the amount of light to be incident upon one pixel of the imager has decreased as the pixel size of the imager has been reduced for the purpose of increasing the resolution. As a result, this leads to a deterioration in the signal-to-noise ratio (S/N) of each pixel, thus making it difficult to maintain the image quality.